PHOTO: In this photo illustration, The Twitter logo is displayed on a mobile device as the company announced it's initial public offering and debut on the NewYorkStockExchange on Nov. 7, 2013 in London.

PHOTO: A Stock trader is seen holding his head at the floor of the NewYorkStockExchange when the Dow Jones dropped over 500 points, the largest decline in modern time, as panic selling swept Wall Street, Oct. 19, 1987.

PHOTO: Quazi Mohammad Rezwanul Ahsan Nafis, 21, a Bangladeshi national, allegedly parked a van filled with what he believed to be 1,000 pounds of explosives outside the building in Lower Manhattan near the NewYorkStockExchange , and was arrested after h